Scanning Autocorrelator AA-M for Multiphoton Microscopy

The AA-M scanning autocorrelator is designed for femtosecond pulse measurement and control during experiments incorporating a microscope or another optical device in the beam path. The autocorrelator measures the duration at the microscope's input as well as at its output at the sample position providing smooth operation and precise experimental results.

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  • External and internal photodetectors
  • Scan rate 0.1-20 Hz
  • USB connection and software in the standard package
  • Bypass function for internal detector beam path
  • Fringe-resolved autocorrelation function


  • Two-photon (multiphoton) microscopy (TPE)
  • SHG/THG (second/third harmonic generation) microscopy
  • Optical coherence tomography
  • Fluorescence spectroscopy of biological markers
  • Pump-probe spectroscopy
  • Laser systems design, integration and amplification
  • Ultrafast laser diagnostics, accessories and components
  • Femtosecond oscillator pulse duration measurement
  • Femtosecond pulse duration measurement and dispersion characterization
  • Comparison of dispersion values, determining dispersion of various optical elements
  • Femtosecond and picosecond pulse duration and near contrast measurement
  • Femtosecond and picosecond OPA pulse duration and near contrast measurement

The AA-M provides two simultaneous measurement points: one at the focal plane of the microscope and the other being the point where the optical head of the device is placed, i.e. somewhere before the microscope input. The comparison of the pulse duration value obtained in these two measurements determines the pulse broadening introduced due the dispersion of the microscope’s optical elements. In most cases of application of ultra-short pulses in microscopy it is essential to characterize the temporal and spatial profile of the beam in the focal spot of the microscope. These measurements are vital for any experiment as the shorter is the pulse the higher is the efficiency of the nonlinear imaging process (2-photon excitation) and less excitation energy is needed for successful experiment. Such beam characterization is also necessary when determining exposition of the sample. It ensures image optimization and correct intensity level estimation, as incorrect values may even lead to sample damage.

The autocorrelator may cover various wavelength ranges, as well as combine the ranges by using 3 interchangeable sets of photodetectors and optics. Two separate ranges can also be covered upon request. Input pulse duration ranges from 20 fs to 12 ps for easy monitoring of different laser systems.

The device features USB interface and can be easily hooked up to a PC with Windows OS. The software is supplied with the device and comprises several useful tools. The acquired pulse duration data can be visualized, stored or exported to a .txt or .dat file. Autocorrelation function and final FWHM pulse duration in femtoseconds are calculated and displayed in real-time. Moreover, Gaussian or sech^2 fitting options are enabled, intensity function may also be observed. The statistical viewer feature allows the comparison of data acquired from several separate pulse measurements.

Model AA-M
Wavelength range 450 - 700 nm (AA-MV)
700 - 1300 nm (AA-M)
1300 - 2000 nm (AA-MR)
450 - 2000 nm (AA-MM) *
Number of photodetectors two (incl. one external)
Pulse duration range 20 fs - 12 ps
Input repetition rate > 10 kHz
Sensitivity 100 mW2
Input polarization, linear horizontal (vertical upon request)
Scanning rate 0.1 - 20 Hz
Linear distortion < 1 %
Collinear (interferometric and intensity) autocorrelation yes
PC connection USB
Necessary equipment PC with Windows OS or oscilloscope
Fiber input (optional) FC/PC or FC/APC (other types available upon request)
Signal source and detector Two-photon conductivity in semiconductor

* AA-MM may cover either all three ranges (450-2000 nm) or two separate ranges (i.e. 450-1300 or 700-2000) with interchangeable optics and photodetectors (3 or 2 sets included).

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TOPAG Lasertechnik GmbH
Nieder-Ramstädter Str. 247
64285 Darmstadt, Germany
Phone: +49 6151 4259 78
Fax: +49 6151 4259 88